<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8"/>
        <title></title>
        <style type="text/css">
            #p1{font-weight:lighter;}
            #p2{font-weight:normal;}
            #p3{font-weight:bold;}
            #p4{font-weight:bolder;}
        </style>
    </head>
    <body>
        <p id="p1">字体粗细为:(lighter)</p>
        <p id="p2">字体粗细为:(normal)</p>
        <p id="p3">字体粗细为:(bold)</p>
        <p id="p4">字体粗细为:(bolder)</p>
    </body>

</html>